1. Field of the Invention
The present invention mainly relates to a wiring board for a semiconductor device for mounting semiconductor elements thereon.
2. Description of the Related Art
In recent years, the size reduction and performance enhancement of electronic equipment have pushed the increase in degree of integration and size reduction of semiconductor elements used in the electronic equipment.
This is achieved, for example, by a connection structure for connection between a substrate and semiconductor elements, in which a conductor pedestal called “land” is provided on the substrate so that a contact member such as a solder ball provided on the land is connected to another substrate or the like.
When employing this structure, the sizes of the land and the contact member must be reduced in order to increase the degree of integration and the number of terminals of the semiconductor elements.
However, the size reduction of the land and contact member inevitably involves the reduction of the contact area, which possibly deteriorates the bonding strength.
Therefore, a structure is required to prevent the deterioration in the bonding strength due to the size reduction of the land and the contact member.
A NSMD (Non Solder Mask Defined) structure is one of such structures to prevent the deterioration in the bonding strength between the land and the contact member.
The NSMD structure is a structure in which a gap is provided between the land and a solder resist, so that the contact member is in contact not only with the top face of the land but also the side faces of the land, whereby the bonding strength between the land and the contact member is enhanced.
However, even in the NSMD structure, a neck portion where a wiring line is led out from the land, that is, a connection portion connected with the wiring line assumes a SMD (Solder Mask Defined) structure covered with a solder resist.
Therefore, the NSMD structure often suffers fracture of the contact member which progresses from the SMD portion (neck) where the connection with the contact member is weak, and thus a structure to prevent such fracture is sometimes required.
The structure to prevent the fracture is for example achieved by a structure in which an annular support portion is provided around the terminal portion of the land and a plurality of joining portions are used to connect between the terminal portion and the support portion.
For example, Japanese Laid-Open Patent Publication No. 2003-243813 (Patent Document 1) shows, in FIG. 1, a terminal structure for a BGA (Ball Grid Array) semiconductor device in which a land for soldering a ball has a terminal portion, a support portion arranged in the vicinity of the outer periphery of the terminal portion, and a joining portion for joining the terminal portion with the support portion, and an insulating layer is provided on the substrate to cover the support portion while leaving the terminal portion exposed, so that the ball is soldered to the terminal portion with the solder extending over the surface of the terminal portion and the edge.